Optical system for facsimile scanner



SEARCu JTDU'FUQ"? United Stat fiUfiaifiiTLb'Egr qtgRrw ss XR 3.475.55310/1969 Reese et .11.... Champaigmlll. 3.487.224 12/1969 Beckmann [2H P768635 Primary E.raminerRichard Murray 1 1 Flled 1968 AssistantE.raminerRichard P. Lange [45] w 9 I Allorney-Richard T. Seeger 173]Assignee The Magnavox Company Fort Wayne, Ind. a corporation of Delaware[54] OPTICAL SYSTEM FOR FACSIMILE SCANNER 9 Claims' 11 Drawing Fig5ABSTRACT: An optical system for the light path In the scanner ofafacsimile scanner 15 mounted in a compact, rotary {52] US. housing Thehousing has a longitudinal bore and two light openings extend along acommon diameter between the bore and the sides of the housing. A plasticlens having a flat aperture surface and a convex surface is mounted inthe bore. A plastic prism having two reflecting surfaces is mounted inthe 178/7.6 H04n l/06 501 Field 178/7.6, 7.1E. 7.1

bore and on the p1astic lens. Light entering the two light openings isreflected by the two reflecting surfaces to the lens aperture surface,and is focused by the convex surface at a selected location.

2.997.539 871961 Blackstone..,............,...

PATENTEU [M129 19m SHEET 1 [1F 3 B M M ATTORNEY m RV mm m m WA R E GPATEF-HEDDEQQIQYB 3.551.595

INVENTOR GERARD o: VRIES OPTICAL SYSTEM FOR FACSIMILE SCANNER BACKGROUNDOF THE INVENTION In one type of facsimile scanner, a beam of light isrotated about an axis to provide a spot of light that moves in onedirection on the document being scanned and the document is moved alongthe axis, so that the document can be completely scanned by the spotoflight. In such a scanner. it is necessary that an optical system beprovided to direct the spot oflight on the document to a light sensitivedevice, which is usually stalionary. The light sensitive device convertsthe light energy into a usable electrical signal. The electrical signalis sent to a facsimile receiver which converts the signal intoappropriate form for reproducing the scanned document. Typically, thescanner optical system has a lens system which rotates in synchronismwith the spot of light, and which directs the spot of light to areflecting surface. The reflecting surface rotates with the lens systemso that light passing through the lens system is reflected and directedto the light sensitive device. The resolution of the scanner, that isthe details of the document that are scanned and transformed into anelectrical signal, is dependent, among other things, upon how small thespot of light can be maintained. Since the lens system and thereflecting surface must rotate in synchronism with the spot of light,the optical accuracy and position of the lens system and the reflectingsurface are relatively critical. Therefore, the lens system andreflecting surface must be accurately designed, and must be constructedso that they maintain their accuracy under relatively adverse fieldconditions. If any element in the lens system or the reflecting surfaceloses its adjustment, it is usually necessary that the scanner bereturned to a repair center or factory in order that it can bereadjusted with the proper equipment.

Accordingly, a primary object of my invention is to provide an improvedoptical system for facsimile scanners having a spot of light thatrotates on a document being scanned for transmission.

Another object of my invention is to provide an improved facsimilescanner optical system that is relatively compact and easy tomanufacture.

Another object of my invention is to provide an improved facsimilescanner optical system that is inherently accurate and that keeps itsadjustment.

Another'object of my invention is to provide an improved facsimilescanner optical system having rotating optical elements positioned atthe center of revolution so that the optical elements have the lowestpossible linear velocity.

Still another object of my invention is to provide an improved scanneroptical system that has a relatively high overall accuracy so that arelatively small light sensitive device may be used.

SUMMARY OF THE INVENTION Briefly, these and other objects are achievedin accordance with my invention by a housing that is positioned on thecentral longitudinal axis of the facsimile scanner and that rotates insynchronism with the scanning spot of light. The housing has alongitudinal bore and one or more transverse light openings between thebore and housing sides. An optical lens having a flat aperture surfaceand a convex focusing surface is positioned in the bore. One or morereflecting surfaces is positioned in the bore and on the lens forreflecting the spot of scanning light that passes through the lightopenings along the longitudinal axis toward the flat aperture surface.The light reaching the flat aperture surface is focused by the convexfocusing surface at a selected location on the longitudinal axis; Afixed light sensitive device positioned at this selected locationconverts the light energy into electrical signals. The housing. thelens. and the reflecting surface are formed with surfaces which interfitso that when the lens and reflecting sur-- face are positioned in thehousing bore. they can be firmly held so that they keep theiradjustment.

BRIEF DESCRIPTION OF THE DRAWING The subject matter which I regard as myinvention is particularly pointed out and distinctly claimed in theclaims. The structure and operation of my invention, together withfurther objects and advantages, may be better understood from thefollowing description given in connection with the accompanying drawing,in which:

FIG. 1 shows a perspective view of a facsimile scanner which can utilizemy improved optical system;

FIG. 2 shows a longitudinal cross-sectional view of an improved opticalsystem in accordance with my invention for use in the scanner of FIG. 1;

FIG. 3 shows a cross-sectional view of the optical system in accordancewith my invention taken along the line 3-3 of FIG.

FIG. 4 shows an exploded perspective view of the improved optical systemof FIGS. 2 and 3;

FIGS. 5a through 5:] shows various views ofa lens used in my improvedoptical system ofFlGS. 2, 3, and 4; and

FIGS. 6a through 60 shows various views of a reflecting prism used in myimproved optical system ofFlGS. 2, 3, and 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, l have shown afacsimile scanner 10 which can utilize my improved optical system. Thescanner 10 shown in FIG. 1 may also include receiving apparatus fortransforming electrical signals into markings on a sheet of paper so asto reproduce a document being scanned at a distant location. Thefacsimile scanner 10 is mounted on a suitable base 11 which supports aconcave cylindrical platen 12 that extends horizontally along the base11 and that receives the document to be scanned. The platen 12 includesmeans for moving the document being scanned parallel to a longitudinalaxis 13 of rotation. A yoke 14 is mounted for rotation about thelongitudinal axis 13, and is rotated by a synchronous electric motor 15.An incandescent lamp 16 and two concave reflecting mirrors 17a, 17b aremounted on the yoke 14 to provide two beams of light. Each ofthese beamsis focused by a respective concave mirror 17a, 17b to a spot that isspaced from the longitudinal axis 13 by a distance equal to the radialdistance between the axis 13 and the platen 12. The two spots are thuslocated at the ends ofa common diameter which rotates about the axis 13as a center. Since the platen 12 is less than a halfof a cylinder, onlyone spot is present on the platen 12 at any instant. The two spotsalternately sweep or scan over the platen l2 and the document positionedon the platen 12. At the same time that the spots scan the document, thedocument is moved parallel to the longitudinal axis 13 at a slower speedso that the spots can scan the entire document. In the scanner 10 shownin FIG. 1, the document is moved on the platen 12. But it is to beunderstood that the document can be held stationary and that the spotsof light can rotate about the axis 13 and can also move parallel to theaxis 13 to obtain a complete scan of a document.

The moving spots of light illuminate a small area of the document beinginstantaneously scanned. The amount oflight reflected from this smallarea of illumination indicates whether the particular area on thedocument is light, dark, or some intermediate shade. This reflectedlight must be directed to a light-sensitive device 18 which converts thereflected light energy into an electrical signal which can betransmitted to a distant location for utilization and reproduction ofthe document. The reflected light is directed toward the axis 13 by apair of pickup lenses 19 which are also mounted on the yoke 14 to rotatein the proper relation relative to the spot. Light from the pickuplenses 19 is directed along the axis 13 by an optical system inaccordance with my invention. This optical system is carried in ahousing 30 which is also mounted on the yoke 14. If the machine of FIG.I is to be used to produce produced by a scanner. Except for the housing30 and the optical system in accordance with my invention, the machineof FIG. 1 as described thus far is known in the art.

In FIGS. 2 and 3, I show detailed views of the housing 30 and theopticalsystem in accordance with my invention. The housing 30 is agenerally cylindrically shaped member formed of metal or plastic, andhas a cylindrical bore 32 extending longitudinally between its ends. Asshown in FIG. 2, the bore 32 has several diameters: a large diameter atthe left end, an intermediate diameter between the ends, and a smalldiameter at the right end. The housing 30 is symmetrically positioned onthe longitudinal axis 13 and fastened to the yoke 14 by means such asmachine screws 33. The housing 30 is provided with two side openings34a, 341: which lie along a diameter of the housing 30 and extendthrough the wall of the housing 30 at substantially a right angle to thelongitudinal axis 13 of the scanner 10. A lens member 40 is positionedin the bore 32 at its intermediate diameter portion. .The lens member 40is generally cylindrical in shape, and is symmetrically positioned onthe longitudinal axis 13. The lens member 40 may be made of any suitableoptical material. Such material may include a transparent plastic, suchas plexiglass for example. The lens member 40 has a cylindrical hole 41extending from its left end toward its right end, and terminating toform an aperture surface 42. At the right end, the lens member 40 isprovided with a projection 43 having a reduced diameter and ending in ahemispherical surface that forms a convex focusing lens. The lens member40 also has a locating hole 44 positioned at the end near the projection43. The locating hole 44 receives an indexing pin 35 positioned in theinterior of the housing 30. At the left end, the lens member 40 isprovided with two diametrically oriented V-shaped notches 45a, 45b forreceiving and positioning a reflecting prism 50. At the same left end,the lens member 40 is also provided with diametrically positioned lightopenings 47a, 47!) which are positioned along a diameter of the lensmember 40 that is perpendicular to the diameter on which the notches45a, 45b are oriented. With the lens member 40 positioned in the housing30 so that its locating hole 44 mates with the indexing pin 35, thelight openings47a,

47b of the lens member 40 are aligned with the side openings 34a, 34b ofthe housing 30. This can be seen in FIG. 3. The reflecting prism 50 iscylindrically shaped and may be made of any suitable material. The prism50 is symmetrically positioned on the longitudinal axis 13. The prism 50has two accurately positioned and formed plane reflecting surfaces 510,

Sib which extend from a vertex 53 positioned on the axis 13 (and atequal angles with respect to the axis 13) outward toward the sides. Thereflecting surfaces 51a, 51b are coated with a good optical reflector,which may be applied by any suitable method. The respective angles ofthe two reflecting surfacesSla, 51b are made as precisely equal aspossible to the two angles forming the V-shaped notches 45a, 45b in thelens member 40. The lens member 40 rests against the surface between theintermediate and right end portion ofthe bore 32, and the reflectingprism 50 rests in the V-shaped notches 45a, 45b. The lens member 40 andthe prism 50 are held by a spring member 36 that is compressed and heldby a locking ring 37 snapped into a groove at the left end of the bore32.

FIG. 4 shows a perspective view of the elements and my housing in adisassembled position. When the elements are as sembled into the housing30, the lens member 40 is positioned in the bore 32 so that its locatinghole 44 mates with the pin 35. This insures that the light openings 47a,47b of the lens member 40 are aligned with the side openings 34a, 34b ofthe housing 30. The reflecting prism 50 is then positioned in the bore32 so that its reflecting surfaces 51a, 51b fit into the respectivenotches 45a, 45!) thus insuring that the reflecting surfaces 51a, 51bare properly positioned to receive light which passes through theopenings 34a, 34b, 47a, 47b. The lens member 40 and the reflecting prism50 are then held by assembly provides a compact and stable structurewhich, as

will be explained, provides an improved optical path.

FIGS. 5a through 5d show more detailed views of the lens member 40, andparticularly the arrangement and orientation of the light openings 47a,47b and the V-shaped notches 45a, 45b FIG. 5a shows a top plan view,FIG. 5b shows a side elevation view, FIG. 5c shows a view from one end,and FIG. 5d shows a view from the other end. in particular, FIG. 5cshows how the light openings 47a, 47b are oriented along a diameterwhich is at right angles with respect to the diameter on which theV-shaped notches 45a, 45b are oriented. As

mentioned, the lens member 40 may be made of suitable optical material,such as glass or transparent plastic. When this material is cast, ormolded, it should be finished so that the aperture surface 42 is asnearly optically flat as possible, and so that the end of the projection43 forms as a lens (in this case a hemisphere) that is as opticallyaccurate as possible. As the optical accuracy is increased, the accuracyof the light waves will also be increased. Likewise, the surfaces of thenotches 45a, 45b should be as flat and accurate as possible so as toposition the reflecting prism 50 as accurately as possible.

FIGS. 60, 6b, and 6c show top, front and side views respectively of thereflecting prism 50. The prism 50 may also be made of a suitablematerial such as a stable plastic like plexiglass. The reflectingsurfaces 51a, 5112 should be as optically flat as possible, and coatedwith the most efficient reflector possible. In addition, the angle thatthese surfaces 51a, 51b

form should be as accurate as possible so that the light waves.

are fixed in position with respect to the mirrors 17a, 17b. Lightreflected from the illuminated spot is transmitted by the pickup lenses19 of FIG. 1 in the direction indicated by the arrows of FIG. 2 throughthe openings 34b, 47 b (or 34a,

. 47a) to the reflecting surface 51b (or 51a) in the direction indicatedby the arrows 71 toward the aperture surface 42. At the aperture surface42, the light is bent in the direction indicated by the arrows 72 towardthe hemispherical surface of the projection 43. At this surface, thelight is bent in the direction indicated by the arrows 73 to a focalpoint ofthe surface. The light sensitive device 18 is positioned in astationary manner at the focal point for converting the light energy toelectrical signals.

It will thus be seen that my invention provides a new and improvedoptical system for use in facsimile scanners. While my system isrelatively simple in construction, it may be made of molded plasticparts that may have sufficient accuracy to require no further machiningor grinding. However, if the parts do require further modification, thismay be easily achieved by known machining techniques. The parts areeasily and quickly assembled in their housing to provide a structurewhich is rigidly held together in an accurate relation, and whichprovides long periods of accurate service. The assembled optical systemmay be easily checked on a jig or other apparatus at the factory, afterwhich it may be used as a new unit or a replacement unit with theassurance that it will perform within the desired accuracy tolerances.If for some reason the parts do become misaligned or broken, they may beeasily replaced in the fi'eld by substituting appropriate parts in thehousing 30, or by substituting a complete housing with the lens member40 and the reflecting prism 50 already mounted. While I have shown onlyone embodiment of my invention, persons skilled in the art willappreciate that modifications may be made. For example, the dimensionsand shape of the optical lens member 40 may be varied to providedifferent focal lengths. The aperture surface 42 may be provided with anopaque mask around a suitable outer portion. The angles of thereflecting surfaces 51a. 51b may be varied. This may be necessary toaccommodate a lens member 40 and a reflecting prism 50 which have anindex of refraction different from plexiglass. The angles of theV-shaped notches 45a, 45b in the lens member 40 should conform with theangles ofthe reflecting surfaces 51a, 51b so that the reflecting prism50 is securely held by the lens member 40. The relative diameters of thebore 32, the lens member 40, and the reflecting prism 50 should providea snug fit when the lens member 40 and the prism 50 are positioned inthe bore 32 With respect to the reflecting prism 50, the angle of thereflecting surfaces 51a, 51b should be such that there is no chance oflight being refracted instead of reflected. The exact shape anddimensions of the openings 47a, 47b in the lens member 40 and theopenings 340, Mb in the housing 30 may also be varied. Therefore, whilemy invention has been described with reference to a particularembodiment, it is to be understood that modifications may be madewithout departing from the spirit ofthe invention or from the scope ofthe claims.

lclaim:

1. An improved optical scanner for use in facsimile apparatus having aplaten for receiving and holding a document to be scanned, having arotating member that rotates about a longitudinal axis for producing amoving spot of light on the document to be scanned, and having a lightsensitive device for receiving light and producing an electrical signaltherefrom, said optical scanner comprising:

a. a housing adapted to be mounted on said rotating member of saidscanner;

b. said housing having a cylindrical bore centered on said longitudinalaxis and extending from one end through said housing to the other end,and said housing having a first light opening extending radially outwardfrom said bore and through an outer surface of said housing;

c. a cylindrical lens member positioned in said bore of said housing;

said lens member having an internal opening extending from one end alongsaid longitudinal axis toward the other end but terminating at anaperture surface that lies in a plane that is substantiallyperpendicular to said longitudinal axis. having a projection at saidother end that forms a convex focusing lens centered on saidlongitudinal axis for focusing light impinging on said aperture surfaceat a selected location on said longitudinal axis for utilization by saidlight sensitive device, having a first light opening extending radiallyoutward from said internal opening to said first light opening in saidhousing, and having a pair of positioning notches in said one end, saidpositioning notches being oriented along a diameter of said lens member;

a cylindrical reflecting member positioned in said bore of said housing.said reflecting member being positioned in said position ng notchesofsaid lens member and having a first reflecting surface oriented toreflect light passing through said first light opening of said housingand said first light opening of said lcns member toward said aper turesurface: and

f means for retaining said reflecting member in said bore and there byretaining said lcns member in said bore.

.2. The improved optical scanner of claim 1, and further comprisingmeans positioned in said bore of said housing for engaging said lensmember and holding said lens member and thereby said reflecting memberin a fixed position in said housing.

3. The improved optical scanner of claim 1 wherein said housing has asecond light opening extending radially outward in the opposite drection from said first light opening through the diametrically oppositeouter surface of said housing, wherein said lens member has a secondlight opening extending radially outward in the opposite direction fromsaid first light opening to said second light opening in said housing.and

wherein said reflecting member has a second reflecting surfacesymmetrtcally oriented with respect to said first reflecting surface toreflect light passing through said second light opening of said housingand said second light opening of said lens member toward said aperturesurface.

t. The improved optical scanner of claim 3. and further comprising meanspositioned in said bore of said housing for engaging said lens memberand holding said lens member and thereby said reflecting member in afixed position in said hous- 5. The improved optical scanner of claim 4wherein said internal opening of said lens member is substantiallycylindrical in shape and is symmetrically positioned about saidlongitudinal axis.

6. An improved optical scanning arrangement for facsimile transmittingapparatus having a yoke structure that is adapted to rotate about anaxis, said optical scanning apparatus comprising:

a. a housing carried by said yoke and having a first bore coaxial withsaid axis and extending from one end of said housing to the other end ofsaid housing, said housing having a second bore extending angularly fromsaid first bore to a side of said housing;

. an optical lens having an aperture at one end and a convex focusingsurface at the other end and positioned in a predetermined axialposition in said first bore of said housing with said one end of saidlens facing said one end of said housing and with said other end of saidlens facing said other end of said housing so that light striking saidaperture of said lens is focused at a selected axial location withrespect to said housing;

c. an optical reflector member having a first reflecting surface, saidreflector member being positioned in said first bore of said housing inspaced relation to said one end of said lens and with said reflectingsurface so located with respect to said second bore of said housing thatlight entering said housing via said second bore is reflected by saidfirst reflecting surface toward said aperture of said lens;

d. means nonrotatively and nonaxially movably mounted in said first borebetween said lens and said optical reflector member and nonrotativelyand abuttingly engaging said optical reflector member on the sidethereof facing said surface of said optical reflector member being sopositioned with respcct to said third bore of said housing that lightentering said housing via said third bore of said housing is reflectedby said second reflecting surface toward said aperture of said lens.

9. The improved scanning arrangement of claim 8 wherein said second andthird bores of said housing have a common axis that is substantiallyperpendicular to the axis of said first bore.

